Gentlemen,
Komatsu never published any such modification for "drain back". Maybe someone out in the field made it up and it was a cheap fix and passed it around, but it was never a Komatsu fix. Komatsu did have a retainer o-ring issue on early "ZB" Series forklifts FG(D)20/25/30T-11 trucks. The fix was to install the new style viton o-ring.
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